High power and data delivery in a communications network with safety and fault protection

ABSTRACT

In one embodiment, a method includes receiving power at an optical transceiver module at a remote network device on a cable delivering power and data from a central network device, operating the remote network device in a low voltage startup mode during fault sensing at the remote network device, transmitting on the cable, a data signal to the central network device, the data signal indicating an operating status based on the fault sensing, and receiving high voltage power from the central network device on the cable at the remote network device upon transmitting an indication of a safe operating status at the remote network device, wherein the remote network device is powered by the high voltage power. An apparatus is also disclosed herein.

TECHNICAL FIELD

The present disclosure relates generally to communications networks, andmore particularly, to safety and fault protection in a communicationsnetwork with combined high power and data delivery.

BACKGROUND

Power over Ethernet (PoE) is a technology for providing electrical powerover a wired telecommunications network from power sourcing equipment(PSE) to a powered device (PD) over a link section. In conventional PoEsystems, power is delivered over the cables used by the data over arange from a few meters to about one hundred meters. When a greaterdistance is needed or fiber optic cables are used, power must besupplied through a local power source such as a wall outlet due tolimitations with conventional PoE. Furthermore, today's PoE systems havelimited power capacity, which may be inadequate for many classes ofdevices.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a network in which embodimentsdescribed herein may be implemented.

FIG. 2 depicts an example of a network device useful in implementingembodiments described herein.

FIG. 3 is a block diagram illustrating components of a power safety andfault protection system, in accordance with one embodiment.

FIG. 4 is a flowchart illustrating an overview of a process for lowvoltage startup with fault detection and digital interlock in a combinedpower and data delivery system, in accordance with one embodiment.

FIG. 5 is a flowchart illustrating an overview of a process for pulsepower with fault detection between pulses in a combined power and datadelivery system, in accordance with one embodiment.

FIG. 6 is a diagram illustrating a circuit for use with pulse loadcurrent and auto-negotiation, in accordance with one embodiment.

FIG. 7 is a timing diagram for the circuit shown in FIG. 6, inaccordance with one embodiment.

FIG. 8 is a diagram illustrating a circuit for use with unipolar pulsepower and auto-negotiation, in accordance with one embodiment.

FIG. 9 is a timing diagram for the circuit shown in FIG. 8, inaccordance with one embodiment.

FIG. 10 is a diagram illustrating a circuit for use with bipolar pulsepower and auto-negotiation, in accordance with one embodiment.

FIG. 11 is a timing diagram for the circuit shown in FIG. 10, inaccordance with one embodiment.

FIG. 12 is a diagram illustrating line-to-ground fault detection, inaccordance with one embodiment.

FIG. 13 is a diagram illustrating line-to-line fault detection, inaccordance with one embodiment.

FIG. 14 is a diagram illustrating line-to-line fault detection, inaccordance with another embodiment.

FIG. 15 is a diagram illustrating line-to-line fault detection, inaccordance with yet another embodiment.

Corresponding reference characters indicate corresponding partsthroughout the several views of the drawings.

DESCRIPTION OF EXAMPLE EMBODIMENTS Overview

In one embodiment, a method includes receiving power at an opticaltransceiver module at a remote network device on a cable deliveringpower and data from a central network device, operating the remotenetwork device in a low voltage mode during fault sensing at the remotenetwork device, transmitting on the cable, a data signal to the centralnetwork device, the data signal indicating an operating status based onthe fault sensing, and receiving high voltage power from the centralnetwork device on the cable at the remote network device upontransmitting an indication of a safe operating status of the remotenetwork device, wherein the remote network device is powered by the highvoltage power.

In another embodiment, a method generally comprises delivering highvoltage direct current (HVDC) pulse power from power sourcing equipmentto a powered device over a cable delivering power and optical data,testing a power circuit between the power sourcing equipment and thepowered device between pulses, and communicating with the powered deviceover the cable to identify an operating mode at the powered device basedon the testing.

In yet another embodiment, an apparatus generally comprises an opticalinterface for receiving optical signals on an optical fiber in a powerand data cable at an optical transceiver, an electrical interface forreceiving power on an electrical wire in the power and data cable at theoptical transceiver for powering the apparatus in a high power mode, anda power module for testing a power circuit and delivering datacomprising an operating status of the power circuit over the power anddata cable to a combined power and data source. The power module isconfigured for testing the power circuit in a low voltage power mode.

Further understanding of the features and advantages of the embodimentsdescribed herein may be realized by reference to the remaining portionsof the specification and the attached drawings.

Example Embodiments

The following description is presented to enable one of ordinary skillin the art to make and use the embodiments. Descriptions of specificembodiments and applications are provided only as examples, and variousmodifications will be readily apparent to those skilled in the art. Thegeneral principles described herein may be applied to other applicationswithout departing from the scope of the embodiments. Thus, theembodiments are not to be limited to those shown, but are to be accordedthe widest scope consistent with the principles and features describedherein. For purpose of clarity, details relating to technical materialthat is known in the technical fields related to the embodiments havenot been described in detail.

In conventional Power over Ethernet (PoE) systems used to simultaneouslytransmit power and data communications, power is delivered over the sametwisted pair cable used for data. These systems are limited in range toa few meters to about 100 meters. The maximum power delivery capacity ofstandard PoE is approximately 100 Watts, but many classes of powereddevices would benefit from power delivery of 1000 Watts or more. Inconventional systems, when a longer distance is needed, fiber opticcabling is used to deliver data and when larger power delivery ratingsare needed, power is supplied to a remote device through a local powersource.

As previously noted, it is desirable to increase the power availableover multi-function cables to hundreds and even thousands of watts. Thiscapability may enable many new choices in network deployments wheremajor devices such as workgroup routers, multi-socket servers, largedisplays, wireless access points, fog nodes, or other devices areoperated over multi-function cables. This capability would greatlydecrease installation complexity and improve the total cost of ownershipof a much wider set of devices that have their power and dataconnectivity needs met from a central hub.

In order to overcome the above issues, power and data delivery systemsmay be designed to carry higher data rates and higher power delivery(and may also carry integrated thermal management cooling) combined intoa single cable, as described in U.S. patent application Ser. No.15/910,203 (“Combined Power, Data, and Cooling Delivery in aCommunications Network”), filed Mar. 2, 2018, which is incorporatedherein by reference in its entirety. These connections may bepoint-to-point, such as from a central hub to one or more remote devices(e.g., full hub and spoke layout). In another example, a single combinedfunction cable may run most of the way to a cluster of powered devicesand then split, as described in U.S. patent application Ser. No.15/918,972 (“Splitting of Combined Delivery Power, Data, and Cooling ina Communications Network”), filed Mar. 12, 2018, which is incorporatedherein by reference in its entirety. With high power applications,further safety concerns arise. Additional fault detection and safetyprotections are needed to prevent a life safety event or an equipmentmalfunction that may cause serious damage.

The embodiments described herein provide high power delivery over a datasystem (also referred to herein as advanced power over data) in acommunications network with fault detection and safety protection (e.g.,touch-safe fault protection). In one embodiment, fault sensing isperformed through a low voltage safety check combined with a digitalinterlock that uses the data system to provide feedback on the powersystem status and set a power operation mode. The fault sensing may beperformed, for example, during a low voltage startup or between highpower pulses in a pulse power system. As described in detail below, thepulse power may comprise source voltage pulse power (unipolar orbipolar) or load current pulse power with low voltage fault detectionbetween high voltage power pulses. Fault sensing may include, forexample, line-to-line fault detection with low voltage sensing of thecable or powered device and line-to-ground fault detection with midpointgrounding. Touch-safe fault protection may also be provided throughcable and connector designs that are touch-safe even with high voltageapplied. The power safety features provide for safe system operation andinstallation and removal (disconnect) of components.

Referring now to the drawings, and first to FIG. 1, an example of anetwork in which embodiments described herein may be implemented isshown. For simplification, only a small number of nodes are shown. Theembodiments operate in the context of a data communications networkincluding multiple network devices. The network may include any numberof network devices in communication via any number of nodes (e.g.,routers, switches, gateways, controllers, access points, or othernetwork devices), which facilitate passage of data within the network.The network devices may communicate over or be in communication with oneor more networks (e.g., local area network (LAN), metropolitan areanetwork (MAN), wide area network (WAN), virtual private network (VPN)(e.g., Ethernet virtual private network (EVPN), layer 2 virtual privatenetwork (L2VPN)), virtual local area network (VLAN), wireless network,enterprise network, corporate network, data center, Internet of Things(IoT) network, Internet, intranet, or any other network).

The network is configured to pass electrical power along with data toprovide both data connectivity and electric power to network devicessuch as switches 14, routers, access points 15, or other electroniccomponents and devices. Signals may be exchanged among communicationsequipment and power transmitted from power sourcing equipment (PSE) 10to powered devices (PDs) 14, 15. As described in detail below, theadvanced power over data system delivers power to and from a network(e.g., switch/router system) using an interface module 16 (e.g., opticaltransceiver module) configured to receive and transmit both data (fiberdelivered data) and electrical power (high power energy). In one or moreembodiments, the power and data may be delivered over a cable comprisingboth optical fibers and electrical wires (e.g., copper wires), asdescribed in U.S. patent application Ser. No. 15/707,976 (“PowerDelivery Through an Optical System”), filed Sep. 18, 2017, which isincorporated herein by reference in its entirety. In one or moreembodiments, the system may further provide cooling and deliver combinedpower, data, and cooling within a single hybrid cable system, asdescribed, for example, in U.S. patent application Ser. Nos. 15/910,203and 15/918,972, referenced above.

As shown in the example of FIG. 1, the advanced power over data systemmay use building power supplied to a central network device (hub) (e.g.,PSE) 10, which may be located in a premise/entry room, for example. Thepower may be transmitted from the building entry point to end points(switches 14, access points 15), which may be located at distancesgreater than 100 meters (e.g., 1 km (kilometer), 10 km, or any otherdistance), and/or at greater power levels than 100 W (watts) (e.g., 250W, 500 W, 1000 W, 2000 W or any other power level). The central networkdevice 10 comprises a power supply unit (PSU) 11 for receiving anddistributing power (e.g., building power from a power grid, renewableenergy source, generator, or battery) and a network interface (e.g.,fabric 12, line cards 13). In the example shown in FIG. 1, line card Areceives data from outside of the building (e.g., from street or otherlocation) and line cards B, C, and D distribute power and data.

The central hub (combined power and data source) 10 is operable toprovide high capacity power from an internal power system (e.g., PSU 11capable of delivering power over and including 5 kW, 100 kW, etc., anddriving the plurality of devices 14, 15, each in the 100 W-3000 W range(e.g., 100 W or greater, 900 W or greater, 1000 W or greater), or anyother suitable power range. The PSU 11 may provide, for example, PoE(Power over Ethernet), PoF (Power over Fiber), HVDC (high voltage directcurrent), pulse power HVDC, or AC (alternating current). The centralnetwork device 10 is operable to receive external power and transmitpower over combined delivery power and data cables 18 in thecommunications network (e.g., network comprising central hub 10 (PSE)and a plurality of network devices 14, 15 (PDs)). The central networkdevice 10 may comprise, for example, a router, convergence system, orany other suitable line card system. It is to be understood that this isonly an example and any other network device operable to transmit powerand optical data may be used. One or more of the line cards 13 may alsoinclude an interface module 16 (shown at the remote network devices 14,15) operable to transmit power and data on the cables 18.

The network may include any number or arrangement of networkcommunications devices (e.g., switches 14, access points 15, routers, orother devices operable to route (switch, forward) data communications).In one example, the network comprises a plurality of groups of accesspoints 15, with each group located on a different floor or zone. One ormore of the network devices 14, 15 may also deliver power to equipmentusing PoE. For example, one or more of the network devices 14, 15 maydeliver power using PoE to electronic components such as IP (InternetProtocol) cameras, VoIP (Voice over IP) phones, video cameras,point-of-sale devices, security access control devices, residentialdevices, building automation devices, industrial automation devices,factory equipment, lights (building lights, streetlights), trafficsignals, fog nodes, IoT devices, sensors, and many other electricalcomponents and devices. In one or more embodiments, a redundant centralhub (not shown) may provide backup or additional power or bandwidth, asneeded in the network. In this case, the remote network device 14, 15would include another interface module 16 for connection with anothercable 18 delivering power and data from the redundant central hub.

As previously noted, the central hub 10 may deliver power and datadirectly to each network device 14 (point-to-point connection as shownfor the switches 14 connected to line cards B and D in FIG. 1) or one ormore splitting devices (not shown) may be used to connect a plurality ofnetwork devices and allow the network to go beyond point-to-pointtopologies and build passive stars, busses, tapers, multi-layer trees,etc. For example, a single long cable 18 may run to a convenientlylocated intermediary splitter device (e.g., passive splitter) servicinga cluster of physically close endpoint devices (e.g., access points 15connected to line card C in FIG. 1). One or more control systems for thepower and data may interact between the central hub 10 and the remotedevices 15 (and their interface modules 16) to ensure that each devicereceives its fair share of each resource from the splitting device, asdescribed in U.S. patent application Ser. No. 15/918,972, referencedabove.

Cables (combined cable, multi-function cable, multi-use cable, hybridcable) 18 extending from the network device 10 to the switches 14 andaccess points 15 are configured to transmit power and data, and includeboth optical fibers and electrical wires. The cable 18 may include, forexample, two power lines (conductors) and two data lines (opticalfibers). It is to be understood that that this is only an example andthe cable 18 may contain any number of power or data lines. For example,instead of using two optical fiber paths to transfer data from thecentral hub 10 to the remote device 14, 15 and from the remote device tothe central hub, a bidirectional optical system may be utilized with onewavelength of light going downstream (from central hub 10 to remotedevice 14, 15) and a different wavelength of light going upstream (fromremote device 14, 15 to central hub 10), thereby reducing the fibercount in the cable from two to one. The cable 18 may also includeadditional optical fibers or power lines. The cables 18 may be formedfrom any material suitable to carry both electrical power and opticaldata (e.g., copper, fiber) and may carry any number of electrical wiresand optical fibers in any arrangement.

As previously noted, the cables 18 may also carry cooling for thermalmanagement of the remote network communications devices 14, 15. Forexample, in one or more embodiments, the cables 18 extending from thecentral hub 10 to the remote network devices 14, 15 may be configured totransmit combined delivery power, data, and cooling in a single cable.In this embodiment, the cables 18 may be formed from any materialsuitable to carry electrical power, data (e.g., copper, fiber), andcoolant (liquid, gas, or multi-phase) and may carry any number ofelectrical wires, optical fibers, and cooling tubes in any arrangement.

The cables 18 comprise a connector at each end configured to couple withthe interface module 16 at the network devices 10, 14, 15. The connectormay comprise, for example, a combined power and data connector (hybridcopper and fiber) configured to connect to an optical transceiver, asdescribed in U.S. patent application Ser. No. 15/707,976, referencedabove. The connector may comprise, for example, a modified RJ-45 typeconnector.

In one or more embodiments, the connector and cable 18 are configured tomeet standard safety requirements for line-to-ground protection andline-to-line protection at relevant high voltage by means includingclearance and creepage distances, and touch-safe techniques. Theconnector may comprise safety features, including, for example,short-pin for hot-plug and hot-unplug without current surge orinterruption for connector arcing protection. The connector may furtherinclude additional insulation material for hot-plug and hot-unplug withcurrent surge or interruption with arc-flash protection and reliabilitylife with arcing. The insulated cable power connector terminals arepreferably configured to meet touch voltage or current accessibilityrequirements.

Each network device 10, 14, 15 comprises an interface module 16(connected to line card 13 at the central network device 10) operable todeliver the combined power and data from the PSE 10 or receive thecombined power and data at the PD 14, 15. In one or more embodiments,the interface module 16 may comprise an optical transceiver moduleconfigured to deliver (or receive) power along with the optical data.For example, in one embodiment, the interface module 16 comprises atransceiver module modified along with a fiber connector system toincorporate copper wires to deliver power through the opticaltransceiver to the powered device 14, 15 for use by the networkcommunications devices, as described in U.S. patent application Ser. No.15/707,976, referenced above or in U.S. patent application Ser. No.15/942,015 (“Interface Module for Combined Delivery Power, Data, andCooling at a Network Device”), filed Mar. 30, 2018, which isincorporated herein by reference in its entirety. It is to be understoodthat these are only examples of interface modules that may be used todeliver or receive high power and optical data.

The interface module 16 (optical module, optical transceiver, opticaltransceiver module, optical device, optics module, silicon photonicsmodule) is configured to source or receive power. The interface module16 operates as an engine that bidirectionally converts optical signalsto electrical signals or in general as an interface to the networkelement copper wire or optical fiber. In one or more embodiments, theinterface module 16 may comprise a pluggable transceiver module in anyform factor (e.g., SFP (Small Form-Factor Pluggable), QSFP (Quad SmallForm-Factor Pluggable), CFP (C Form-Factor Pluggable), and the like),and may support data rates up to 400 Gbps, for example. Hosts for thesepluggable optical modules include line cards 13 on the central networkdevice 10, switches 14, access points 15, or other network devices. Thehost may include a printed circuit board (PCB) and electronic componentsand circuits operable to interface telecommunications lines in atelecommunications network. The host may be configured to perform one ormore operations and receive any number or type of pluggable transceivermodules configured for transmitting and receiving signals.

Also, it may be noted that the interface module 16 may be configured foroperation in point-to-multipoint or multipoint-to-point topology. Forexample, QFSP may breakout to SFP+. One or more embodiments may beconfigured to allow for load shifting. The interface module 16 may alsobe configured for operation with AOC (Active Optical Cable) and formfactors used in UWB (Ultra-Wideband) applications, including forexample, Ultra HDMI (High-Definition Multimedia

Interface), serial high bandwidth cables (e.g., thunderbolt), and otherform factors.

The interface module (optical transceiver) 16 provides for power to bedelivered to the switches 14 and access points 15 in locations wherestandard power is not available. The interface module 16 may beconfigured to tap some of the energy and make intelligent decisions sothat the power source 10 knows when it is safe to increase power on thewires without damaging the system or endangering an operator, asdescribed below. The interface module 16 may include one or moresensors, monitors, or controllers for use in monitoring and controllingthe power and data, as described in detail below with respect to FIG. 3.

In one or more embodiments, there is no need for additional electricalwiring for the communications network and all of the networkcommunications devices operate using the power provided by the advancedpower over data system. In addition to the network devices 14, 15comprising interface modules 16 operable to receive and transmit powerover electrical wires and optical data over fibers, the network may alsoinclude one or more network devices comprising conventional opticalmodules that only process and transmit the optical data. These networkdevices would receive electrical power from a local power source such asa wall outlet. Similarly, specialized variants of transceivers 16 mayeliminate the optical data interfaces, and only interconnect power(e.g., moving data interconnection to wireless networks). As previouslynoted, one or more of the network devices may also receive cooling overcable 18 in addition to power, data, or power and data.

In one or more embodiments, a distributed control system comprisingcomponents located on the central hub's controller and on the remotedevice's processor may communicate over the fiber links in the combinedcable 18. Monitoring information from power sensors (e.g., current,voltage) or data usage (e.g., bandwidth, buffer/queue size) may be usedby the control system in managing or allocating power or data.

As previously noted, the advanced power over data system may beconfigured to deliver PoE, PoF, high voltage DC (HVDC), AC power, or anycombination thereof. The HVDC power may comprise steady state HVDC orpulse power HVDC. The steady state and pulse power HVDC may be unipolaror bipolar (switching DC). In one or more embodiments, the system mayemploy a dual-power mode that detects and negotiates between the powersource 10 and powered device 14, 15, as described below with respect toFIG. 3. This negotiation distinguishes between and accommodatesdifferent power-delivery schemes, such as standard PoE or PoF, highpower, pulse power, or other power modes capable of power deliverythrough the interface module 16. For example, standard PoE distributionmay be used for remote network devices rated less than about 100 W. Forhigher power remote powered devices, pulse power or other higher voltagetechniques may be used to create an efficient energy distributionnetwork.

The remote network device 14, 15 may use a small amount of power atstartup to communicate its power and data requirements to the centralnetwork device 10. The powered device 14, 15 may then configure itselfaccordingly for full power operation. In one example, power type, safetyoperation of the module, and data rates are negotiated between thecentral hub 10 and network device 14, 15 through data communicationssignals on the optical fiber. The interface module 16 communicates anyoperational fault, including the loss of data. Such fault may result inpower immediately being turned off or switching to a low power (lowvoltage) mode. Full power supply may not be reestablished until thepowered device is able to communicate back in low power mode that higherpower may be safely applied.

As described in detail below, the advanced power over data system maytest the network devices or cables to identify faults or safety issues.In one embodiment, a low voltage power mode may be used during startup(or restart) to test the network and components (as described below withrespect to the flowchart of FIG. 4). In another embodiment, testing isperformed between high voltage pulses in a pulse power system (asdescribed below with respect to the flowchart of FIG. 5). The off timebetween pulses may be used for line-to-line resistance testing forfaults and the pulse width may be proportional to DC line-to-linevoltage to provide touch-safe fault protection (e.g., about lms at about1000V).

The testing (fault detection, fault protection, fault sensing,touch-safe protection) may comprise auto-negotiation between the PSE(central hub 10) and PDs (remote network devices 14, 15). For example,the network may be configured using auto-negotiation before receiving adigital indication (interlock) that it is safe to apply and maintainhigh power. The auto-negotiation may comprise low voltage sensing of aPD power circuit or cable for line-to-line fault detection (describedbelow with respect to FIGS. 13 and 14). Low voltage (e.g., less than orequal to 12 VDC (volts direct current), 5-12 VDC, or any other suitablelow voltage (e.g., >60 VDC)) resistance analysis may be used forauto-negotiation. The pulse power high voltage DC may be used with apulse-to-pulse decision for touch-safe line-to-line fault interrogationbetween pulses for personal safety. Line-to-line touch shock protectionmay be provided with a source pulse off-time between pulses forresistance across line detection between pulses.

Ground-fault-detection (GFD) and ground-fault-isolation (GFI)line-to-ground fault detection may be performed to provide fast highvoltage interruption with ground fault protection (shock protection)during high voltage operation as part of using a high-resistancemid-point ground circuit (described below with respect to FIG. 12). Ahigh voltage DC supply line-to-ground fault protection circuit may beused to turn off power quickly to provide touch-safe shock protection.GFD and GFI may provide shut off in approximately 10 μs (microseconds),for example. A midpoint grounding method by the power source may also beused to allow higher peak pulse line-line voltage within thewire/conductor insulation and isolation ratings for line-groundprotection and also provide touch-safe line-to-ground fault for personalsafety and to meet safety standards. The system may also be designed foradjustable time and current versus voltage for personal shockprotection.

The system may be configured to meet safety standards, including, forexample, IEC (International Electrotechnical Commission) standard Nos.62368-3:2017 (“Audio/video information and communication technologyequipment—Part 3: Safety aspects for DC power transfer throughcommunication cables and ports”), IEC 60950-1:2005 (“Informationtechnology equipment—Safety—Part 1: General requirements”), IEC 60947(“Low-voltage switchgear and controlgear”), or any other applicablestandard to provide touch-safe shock protection for personnel for highvoltage (higher power) applications in the advanced power over datasystem. The system may be configured, for example, to limit shockcurrent with line-to-ground fault limit of about 5 mA (e.g., less than10 mA) and line-to-line fault limit of about 0.5 A for 1 ms using about2.5 kohms across HVDC power. Appropriate techniques (e.g., fail-safeSafety Agency Approved Listed components, redundant circuits orcomponents) may be employed in order to meet safety standards. Theembodiments described herein may be configured to meet single faultprotection or other safety requirements. It is to be understood that thestandards and limits discussed herein are only provided as examples andother safety limits or standards may be used, without departing from thescope of the embodiments.

It is to be understood that the network devices and topology shown inFIG. 1, and described above is only an example and the embodimentsdescribed herein may be implemented in networks comprising differentnetwork topologies or network devices, without departing from the scopeof the embodiments. For example, the network may comprise any number ortype of network communications devices that facilitate passage of dataover the network (e.g., routers, switches, gateways, controllers),network elements that operate as endpoints or hosts (e.g., servers,virtual machines, clients), and any number of network sites or domainsin communication with any number of networks. Thus, network nodes may beused in any suitable network topology, which may include any number ofservers, virtual machines, switches, routers, or other nodesinterconnected to form a large and complex network, which may includecloud or fog computing. Nodes may be coupled to other nodes or networksthrough one or more interfaces employing any suitable connection, whichprovides a viable pathway for electronic communications along withpower.

FIG. 2 illustrates an example of a network device 20 (e.g., central hub10, switch 14, access point 15 in FIG. 1) that may be used to implementthe embodiments described herein. In one embodiment, the network device20 is a programmable machine that may be implemented in hardware,software, or any combination thereof. The network device 20 includes oneor more processors 22, memory 24, interface 26, optical module 28 (e.g.,power+optics interface module 16 in FIG. 1), and power module(controller) 29. The network device may also comprise one or morecooling components 21 (sensors, control valves, pumps, etc.) if thesystem is configured for combined power, data, and cooling delivery.

Memory 24 may be a volatile memory or non-volatile storage, which storesvarious applications, operating systems, modules, and data for executionand use by the processor 22. For example, components of the opticalmodule 28 (e.g., code, logic, or firmware, etc.) may be stored in thememory 24. The network device 20 may include any number of memorycomponents.

The network device 20 may include any number of processors 22 (e.g.,single or multi-processor computing device or system), which maycommunicate with a forwarding engine or packet forwarder operable toprocess a packet or packet header. The processor 22 may receiveinstructions from a software application or module, which causes theprocessor to perform functions of one or more embodiments describedherein. The processor 22 may also operate one or more components of thepower control module 29 for fault detection, auto-negotiation, digitalinterlock, etc. The control system may comprise components (modules,code, software, logic) located at the central hub 10 and the remotedevice 14, 15, and interconnected through the combined power and datacable 18 (FIGS. 1 and 2). The control system may also receive input frompower sensors or data monitoring devices, as described below withrespect to FIG. 3. The power module 29 may communicate with the controlsystem at the central network device 10 to auto-negotiate the status ofthe power system, identify any faults in the power system (e.g., cablesor powered device), and select a power operating mode. As previouslynoted, the auto-negotiation may be performed during a low voltagestartup or between pulses in a pulse power system. One or more controlsystem or power module components may be located at the optical module28.

Logic may be encoded in one or more tangible media for execution by theprocessor 22. For example, the processor 22 may execute codes stored ina computer-readable medium such as memory 24. The computer-readablemedium may be, for example, electronic (e.g., RAM (random accessmemory), ROM (read-only memory), EPROM (erasable programmable read-onlymemory)), magnetic, optical (e.g., CD, DVD), electromagnetic,semiconductor technology, or any other suitable medium. In one example,the computer-readable medium comprises a non-transitorycomputer-readable medium. Logic may be used to perform one or morefunctions described below with respect to the flowcharts of FIGS. 4 and5. The network device 20 may include any number of processors 22.

The interface 26 may comprise any number of network interfaces (linecards, ports, connectors) for receiving data or power, or transmittingdata or power to other devices. The network interface may be configuredto transmit or receive data using a variety of different communicationsprotocols and may include mechanical, electrical, and signalingcircuitry for communicating data over physical links coupled to thenetwork interfaces. For example, line cards may include port processorsand port processor controllers. The interface 26 may also comprise fluidports if the system is configured for cooling. One or more of theinterfaces 26 may be configured for PoE+F+C (Power overEthernet+Fiber+Cooling), PoE+F, PoE, PoF, or similar operation.

The optical module 28 may include logic, firmware, software, etc. foruse in monitoring or controlling the advanced power over data system, asdescribed below. For example, the optical module 28 may comprisehardware or software for use in power detection, power monitor andcontrol, or power enable/disable. The optical module 28 may furthercomprise one or more of the processor or memory components, or interface26 for receiving or delivering power and data. As previously described,power is supplied to the optical module by power supply 27 and theoptical module 28 provides power to the rest of the components at thenetwork device 20.

It is to be understood that the network device 20 shown in FIG. 2 anddescribed above is only an example and that different configurations ofnetwork devices may be used. For example, the network device 20 mayfurther include any suitable combination of hardware, software,algorithms, processors, devices, components, or elements operable tofacilitate the capabilities described herein.

FIG. 3 is a block diagram illustrating components for use in powermonitor and control, auto-negotiation, and fault protection at a networkdevice 30, in accordance with one embodiment. One or more of thecomponents shown in FIG. 3 may be located at the interface module 16 orin communication with one or more components of the interface module(FIGS. 1 and 3). The cable 18 carrying the high power and data is shownwith cable connector 36 coupled to the interface module in FIG. 3. Thepower is received at an electrical interface 37 and the data is receivedand transmitted at an optical interface 38. Connector 36 may comprise asingle physical component or a single component with modular parts foreach function, for example.

The network device 30 includes optical/electrical components 31 forreceiving optical data and converting it to electrical signals (orconverting electrical signals to optical data) and power componentsincluding, power detection modules 32 a, 32 b, power monitor and controlmodules 33, and power enable/disable modules 34. Although PoE and pulsepower are described in conjunction with detection elements 32 a, 32 b,it should be understood that other power delivery schemes including AC,DC, and USB may be supported with similar elements. The power componentsmay be isolated from the optical components 31 via an isolationcomponent (e.g., isolation material or element), whichelectromagnetically isolates the power circuit from the opticalcomponents to prevent interference with operation of the optics. Thenetwork device 30 includes an auto detection module 35 that operateswith the pulse power detection module 32 a and PoE detection module 32b. One or more functions of the detection elements 32 a, 32 b, autodetection module 35, power monitor and control modules 33, orauto-negotiation module 39 (described below) may be combined into apower module and operate within the interface module.

The auto-negotiate/digital interlock module 39 may be used in performingone or more fault detection, auto-negotiation, or digital interlockprocesses described herein. As described in detail below,auto-negotiation may include communication between the central networkdevice and the remote network device and interaction between controllersat the central network device and remote network device. One or morecontrol signals or monitoring information may be transmitted over thedata line (e.g., optical fibers) in the combined power and data cable 18to provide an operating status (e.g., fault/no fault) of the networkdevice, cable, or power circuit.

In the example shown in FIG. 3, each module 32 a, 32 b is incommunication with its own power monitor and control module 33 and powerenable/disable module 34. The circuit detects the type of power appliedto the network device 30, determines if PoE or pulsed power is a moreefficient power delivery method, and then uses the selected powerdelivery mode. As noted above, additional modes may support otherpower+data standards (e.g., USB (Universal Serial Bus)).

The network device 30 is configured to calculate available power andprevent the cabling system from being energized when it should not bepowered. The power monitor and control modules 33 continuously monitorpower delivery to ensure that the system can support the needed powerdelivery and no safety limits (e.g., voltage, current) are exceeded. Thepower monitor and control modules 33 may also monitor optical signalingand disable power if there is a lack of optical transitions orcommunication with the power source. Power monitor and control functionsmay sense the voltage and current flow, and report these readings to acentral control function. In one embodiment, the network device 30 usesa small amount of power (e.g., ≤12V, ≤60V) at startup or restart tocommunicate its power and data requirements and status. The networkdevice 30 may then be configured for full power operation (e.g., >60V,≥500V, ≥1000V) (e.g., at high power enable/disable module 34) if nofaults or safety conditions are detected. If a fault is detected, fullpower operation may not be established until the network devicecommunicates in low power mode that high power can be safely applied. Asdescribed below, the auto-negotiate (fault detection module) 39 may beused to test the network and components for touch-safe interrogationbetween pulses in a pulse power system or during a low voltage startupmode. The auto-negotiation module 39 communicates with a control systemat the central network device to select a safe operating mode (e.g.,determine that it is safe to apply high voltage power), identify a faultin the circuit (e.g., line-to-line or line-to-ground fault detection),and shutdown power if a fault is identified.

FIG. 4 is a flowchart illustrating an overview of an auto-negotiationstartup process with safety interlock, in accordance with oneembodiment. At step 40, a remote network device (e.g., switch 14 inFIG. 1) receives combined delivery power and data from a central networkdevice (e.g., combined power and data source 10 in FIG. 1). The power isreceived at an optical transceiver module 16. The remote network device14 operates in a low voltage startup mode during fault sensing(detection) at the remote network device (step 42). The low voltage modemay be, for example, ≤12V (volts), for example. The fault sensing may beperformed to check the operational status of a power circuit extendingbetween the central network device 10 over the combined delivery cable18 to the remote network device 14. As described below, the faultsensing may be performed using control circuits at the remote networkdevice 14, central network device 10, or both network devices. Theremote network device 14 transmits a data signal to the central networkdevice 10 over the combined delivery cable 18 indicating an operatingstatus based on the fault sensing (step 44). This may include, forexample, an auto-negotiation process (auto-negotiating) performedbetween the central network device 10 and remote network device 14. Ifno faults are present at the network device, the remote network deviceconverts to high power operation and a digital interlock is set betweenthe central network device 10 and remote network device 14 (steps 46 and48). The high power operation may comprise, for example, power ≥100V,≥500V, about 1000V (differential voltage), ≥100 W, about 1000 W (loadpower), or any other suitable high power. The remote network device 14receives high voltage power from the central network device 10 on thecable 18 upon transmitting an indication of a safe operating status atthe remote network device, and the network device is powered by the highvoltage power. If a fault is detected, the process may be repeated aftera specified interval or for a specified number of times to determine ifthere was an error in the testing or a fault is still present in thepower circuit. As described below with respect to FIG. 5, a pulse loadcurrent may be applied at the remote network device 14 and faultdetection performed between pulses after the startup process isperformed.

FIG. 5 illustrates an overview of a fault protection process using faultsensing between power pulses in a combined delivery power and datasystem, in accordance with one embodiment. At step 50 a PSE (e.g.,central hub 10 in FIG. 1) delivers high voltage direct current (HVDC)pulse power to a powered device (e.g., remote network device 14 inFIG. 1) over a cable 18 delivering power and data. A power circuitbetween the PSE and PD is tested between pulses (step 52). The PSEcommunicates with the PD over the cable to identify an operating mode atthe PD 14 based on the testing (step 54). If no faults are detected, thePD 14 operates with HVDC pulse power and the process continues withfault detection and auto-negotiation performed between pulses. If afault is detected, power to the PD may be shut-off or the PD may switchto a low power mode. As described below, the pulse power may be HVDCload pulse power (FIGS. 6 and 7), source unipolar pulse power (FIGS. 8and 9), or source bipolar (switched) power (FIGS. 10 and 11).

It is to be understood that the processes shown in FIGS. 4 and 5 anddescribed above are only examples and that steps may be added, modified,removed, or combined, without departing from the scope of theembodiments.

FIGS. 6, 8, and 10 illustrate examples of circuits that may be used forfault detection with pulse power in the advanced power over data systemdescribed herein. FIG. 6 illustrates a circuit that may be used withHVDC pulse load current with off-time auto-negotiation and shut-down fortouch-safe protection. FIGS. 8 and 10 illustrate circuits that may beused with HVDC unipolar source pulse power and HVDC bipolar source pulsepower, respectively, with cable discharge pulse and open circuitoff-time fault sensing and auto-negotiation. FIGS. 7, 9, and 11illustrate timing examples for auto-negotiation in the circuits shown inFIGS. 6, 8, and 10, respectively. As previously described, a low voltagestartup process may be performed to check for faults at startup beforepulse power is applied and auto-negotiation is performed between pulses.The low voltage testing (at startup or between pulses) may include lowvoltage line-to-line sensing, as described below with respect to FIGS.13 and 14. In addition to the low voltage sensing, a high voltage,line-to-ground test may be performed, as described below with respect toFIG. 12.

FIG. 6 illustrates a circuit for use with HVDC pulse load current withoff-time auto-negotiation, in accordance with one embodiment. The inputpower is received at an isolation stage 60 at the PSE, generallyindicated at 61, and output power is delivered at an isolation stage 62at the PD, generally indicated at 63. The PSE 61 provides power to thePD 63 over a combined power and data cable, generally indicated at 65,which in this example comprises a 4 pair cable (e.g., 100 m, 4 paircable, or any other suitable cable configured to deliver high voltagepower and data). The PSE 61 may provide, for example, regulated orunregulated 550 VDC with a 1 KW load and +/−275 VDC power (e.g., about1042 W, 543V, 1.92 A at the PD 63). The steady state power may beunipolar or bipolar. It is to be understood that the power, voltage,current values, and cable described herein are only provided as examplesand that high voltage power may be provided at different power levels orother cable configurations may be used over different distances withoutdeparting from the scope of the embodiments.

As shown in FIG. 6, the PSE 61 includes a sensing/control circuit 64 andthe PD 63 includes a soft-start/voltage control circuit 66. Thesoft-start/voltage control circuit 66 may be used, for example, to limitthe voltage applied at the powered device during startup. The PSE 61further comprises a PSE modulator switch Q1, source capacitor Cs,resistors R1, R2, R3 and auto-negotiate current sense circuit 69. The PD63 portion of the power circuit comprises a load capacitor Cl, diode D1,inductor L1, and PD isolation modulator switch Q2. Switches Q1, Q2 maycomprise, for example, a solid state switch or any other suitabledevice. In one example, PSE switch Q1 is switched on to providecontinuous HVDC power unless a fault is detected during auto-negotiationof cable resistance when PD isolation switch Q2 is switched off, asdescribed below with respect to the timing diagram shown in FIG. 7.

It is to be understood that the circuit shown in FIG. 6 is only anexample and that other arrangements or combinations of components (e.g.,resistors (R1, R2, R3), capacitors (Cs, Cl), diodes (D1, D2), inductor(L1), switches (Q1, Q2), or number of pairs in cable) may be usedwithout departing from the scope of the embodiments.

FIG. 7 illustrates an example of a timing diagram for auto-negotiationin the circuit of FIG. 6, in accordance with one embodiment. As shown inFIG. 7, Q1 voltage is on and continuous (as indicated at 70) until afault is detected during Q2 off-time. In this example, Q2 on-time (72)is 1.0 ms (millisecond). The resistance analysis and auto-negotiationtime (74) is 100 μs (microsecond). If no faults are identified duringthe analysis and auto-negotiation period 74, the cycle is repeated withQ2 on for 1.0 ms (72). In this example, the period covers 1.1 ms with a90.9% duty cycle.

In another example, PSE switch Q1 in FIG. 6 may be switched on for ahigh voltage pulse (e.g., for 1 ms) and switched off (e.g., for 100 μs)for auto-negotiation of cable resistance with PD isolation switch Q2off. Voltage may be measured across the capacitors Cs, Cl duringtesting. When the switches Q1, Q2 are turned off (circuit open), thevoltage across the capacitor Cl will decay as it is discharged throughthe resistor. If the voltage decays too quickly or too slowly, a faultmay be present. Calculated line resistance may also be used and comparedto a specified value to determine if there is a fault in the powercircuit (cable, PSE, or PD). In one example, R1 and R2 may be rated at560 kohms each and the auto-negotiate current sense circuit 69 maycomprise a 220 kohm resistor R3 and 12V power. It should be noted thatthese values are only provided as examples and other resistance orvoltage values may be used.

FIG. 8 shows a circuit for use with HVDC unipolar source pulse power, inaccordance with one embodiment. The system provides cable dischargepulse and open circuit off-time fault sensing line-to-ground orline-to-line abnormal resistance auto-negotiate for touch-safeprotection. As described above with respect to FIG. 6, the input poweris received at an isolation stage 80 of the PSE, generally indicated at81, and power is output from an isolation stage 82 at the PD, generallyindicated at 83. The source 80 operates as both a low voltage source forstartup (e.g., 56 VDC or other low voltage (≤60 VDC)) and a high voltagesource (e.g., 250-550 VDC) for pulsing with switch Q1 operating as amodulator. The PSE 81 and PD 83 communicate over a combined high powerand data cable, generally indicated at 85. The PSE 81 includes asensing/control circuit 84 and the PD 83 includes a soft-start/voltagecontrol circuit 86. The sensing control circuit 84 may includetouch-safe circuits for line-to-line shock with low voltage (e.g., about12-56V) and measures resistance at the PD as an interlock connection toenable high voltage startup and auto-negotiation between pulses withtouch shock protection (e.g., 1-10 kohm) that inhibits the next highvoltage pulse. The sensing circuit 84 may also include touch-safecircuits for line-to-ground shock with high resistance midpoint groundunbalance that inhibits high voltage during pulse.

As shown in FIG. 8, the PSE 81 comprises switches Q1 and Q2, capacitorCs, and resistors R1 and R2. Cable discharge transistor Q2 mayincorporate controlled turn-on or other means to limit peak dischargecurrent and cable ringing. In one example, the PSE 81 provides 1000 VDCfor a 1 kW load at the PD 83 with +1.1 kV pulse power. The PD circuitcomprises a capacitor Cf, diode Dfw, inductor Lf, resistor R3 (for PDconnection resistor detect), and switch Q3. Switch Q3 may providesoft-start, off-time isolation, and regulation. In one example,resistors R1 and R2 comprise 560 kohms resistors and R3 is a 100 kohmresistor.

It is to be understood that the circuit shown in FIG. 8 is only anexample and that other arrangements or combinations of components (e.g.,resistors (R1, R2, R3), capacitors (Cs, Cf), diode (Dfw), inductor (Lf),or switches (Q1, Q2, Q3)) may be used without departing from the scopeof the embodiments. Also, different resistance or voltage values may beused.

FIG. 9 shows a timing diagram with a 1.0 ms-on/0.1 ms-off duty cycle forthe circuit shown in FIGS. 8. Q1 and Q3 power on-time in this example is1.0 ms (indicated at 90). The Q2 cable discharge time (92) is 50 μs andthe resistance analysis and auto-negotiation time (94) is 50 μs. Thisperiod is repeated every 1.1 ms for a 90.9% duty cycle.

FIG. 10 illustrates a circuit for use with HVDC bipolar pulse power inaccordance with one embodiment. The system provides cable dischargepulse open circuit off-time fault sensing line-to-line or line-to-groundabnormal resistance auto-negotiate for touch-safe protection, Thecircuit includes isolation stage 100 at the PSE, generally indicated at101, and isolation stage 102 at the PD, generally indicated at 103. ThePSE 101 and PD 103 are in communication over combined power and datacable, generally indicated at 105. In one example, the current may belimited to about 1-1.2 amps to allow use of a 4-pair cable. The PSE 101comprises a sensing/control circuit 104 and the PD 103 includes asoft-start/voltage control circuit 106, as previously described. The PSE101 comprises switches Q1, Q2, Q3, Q4 that may be used to provide a lowvoltage startup or fault detection between pulses, as described belowwith respect to FIG. 11. The PSE power circuit further includesresistors R1, R2 (e.g., 560 kohm or any other suitable resistance), andan auto-negotiate current sense circuit 109, which may provideresistance (R3) (e.g., 220 kohm or other suitable resistance) and 12V(low voltage) power. In the example shown in FIG. 10, the low voltageauto-negotiate current sense circuit further includes a high voltageblocking switch (Q5).

It is to be understood that the circuit shown in FIG. 10 is only anexample and that other arrangements or combinations of components (e.g.,resistors (R1, R2, R3), capacitors (C1, C2, C3, C4), diodes (D1, D2, D3,D4), inductors (L1, L2), and switches (Q1, Q2, Q3, Q4, Q5) may be usedwithout departing from the scope of the embodiments.

FIG. 11 illustrates a timing diagram for the circuit shown in FIG. 10,in accordance with one embodiment. Q1/Q4 power is on for 0.5 ms (110)and Q3/Q2 power is on for 0.5 ms (112). Q2/Q4 cable discharge time (114)is 50 μs and resistance analysis and auto-negotiation time (116) is 50μs. The 1.1 ms time period is repeated for a 90.9% duty cycle.

It is to be understood that the timing diagrams shown in FIGS. 7, 9, and11 are only examples and that the timing or duty cycle may be differentthan shown without departing from the scope of the embodiments. Forexample, the pulse power duty cycle may be between 90% and 95%.

FIGS. 12-13 illustrate examples of touch-safe protection fromline-to-ground (FIG. 12) and line-to-line (FIGS. 13 and 14) electricalshock. In one or more embodiments, a midpoint grounding line-ground(GFI/GFD) shock protection sensing circuit may be used during highvoltage operation. Line-to-ground (GFI/GFD) fault sensing may also beprovided during low voltage operation to prevent a high voltage pulse.In one or more embodiments, high voltage pulse power is only allowedafter auto-negotiation of safe PD connection (e.g., secure with PDresistance value of about 100 kohms) and no line-to-line body resistancefault (e.g., less than about 8 kohms at startup and for next highvoltage pulse). This minimizes the chance for any contact with exposedelectrical contacts. The short high voltage pulse time before anotherauto-negotiation period between high voltage pulses mitigates the riskof high unsafe currents and electric shock danger.

FIG. 12 illustrates line-to-ground fault detection, in accordance withone embodiment. In one example, the PSE provides source regulated orunregulated HVDC (e.g., 550 VDC) and the PD has load regulated HVDC(e.g., 215 VDC). The PSE and PD are connected over a combined deliverypower and data cable, as previously described. The line-to-ground faultdetection may be used with continuous power or with pulse power when thehigh voltage is on. Fast high voltage interruption is provided withground fault protection (shock protection) during high voltage. In oneexample, 800 k-1.4 k-8 kohms body resistance at 550 VDC for about 1 mA,results in an interrupt in <1 ms. A PSE control circuit 120 controls aPSE pulse modulator switch Q1, PSE cable discharge switch Q2, and GF(ground fault) comparators 124. PD control circuit 122 controlsconverter isolation switch Q3 that has an initial low voltage startupdelay before turn-on with the low voltage power, or wait for the firsthigh voltage pulse to startup. The PD DC/DC converter isolation switchQ3 isolates the DC/DC converter high and low voltages from the lowvoltage auto-negotiation line-to-line circuit sensing the cable circuitresistance for safe PD connection and no low resistance of a bodyresistance fault. This switch circuit may include operation as asoft-start inrush control, reverse polarity protection and also as a PWM(pulse-width modulation) voltage controller. The PD power circuit alsoincludes a PD connection resistor detect resistor R1.

FIGS. 13 and 14 illustrate two examples of circuits for use inline-to-line fault detection. High voltage touch-safe protection isprovided for line-to-line shock for pulse power applications while lowvoltage is on between high voltage pulses or low power mode duringstartup. For example, during startup auto-negotiation may be performedusing sensing of PD connection with correct resistor detection. Lowvoltage auto-negotiation may also be performed for line-to-line faultprotection (shock protection) before next high voltage pulse. In oneexample, 800 k-1.4 k-8 kohms body resistance is assumed during lowvoltage test before next pulse. The circuits shown in FIGS. 13 and 14each include control circuits 130, 132 at the PSE and PD, respectively.In the circuit shown in the example of FIG. 13, a fault sense comparator134 and current sense amplifier 136 are used in line-to-line faultdetection at the PSE. In the circuit shown in the example of FIG. 14,fault sensing is performed to identify an open cable (e.g., about11.1V), cable to PD fault (e.g., about 6.5V), or body fault (e.g., lessthan about 1.8V). The PSE circuit includes a PSE pulse modulator switchQ1 and PSE cable discharge switch Q2. The PD circuit includes PD DC/DCconverter isolation switch Q3 and resistor R1 for use in PD connectorresistor detection, as previously described.

FIG. 15 illustrates another example of a circuit for use in line-to-linefault detection, in accordance with one embodiment. High voltage isturned off and the PD load circuit is isolated, as previously described.The cable voltage capacitance discharge RC-time for resistance is thenevaluated to characterize the normal or safe cable capacitance and thecircuit resistances. Auto-negotiation is performed during high voltageoff time for line-line fault protection (shock protection) before nexthigh voltage pulse by looking at the cable capacitance voltage RC-timedroop slope to an unsafe (fault) level. The circuit includes sourcecontrol circuit 150, load control circuit 152 and auto-negotiate logic154. The source control circuit 150 performs fault sensing with theauto-negotiate logic 154, PSE modulator switch Q1, and crowbar cabledischarge switch Q2. The load control circuit 152 is in communicationwith PD DC/DC converter isolation switch Q3. The auto-negotiate logicincludes a process for determining capacitance of the cable. In oneembodiment, a safe-level off-time/RC time voltage droop level isestablished based on the R5 PD detect resistance of 100 kohm, forexample, with actual cable capacitance at initial startup with firsthigh voltage pulse. Auto-negotiation is then performed for subsequentoff-time RC time droop level. In one example, if the droop level is <10times the safe level from a resistance example of <10 kohm then it is afault-level and there is no next high voltage pulse, and then trigger Q2crowbar/discharge of cable capacitance voltage is set to a safe level.In this example, the source includes resistors R1, R2, R3, R4 (e.g., R1and R4 at 560 kohm, and R2 and R3 at 10 kohm). The load circuit includesinductor Lf, capacitor Cf, and PD connection resistor detect R5 (e.g.,100 kohm).

It is to be understood that the circuits shown in FIGS. 12, 13, 14, and15 are only examples and that other arrangements or combinations ofcomponents (e.g., resistors, capacitors, diodes, inductors, or switches)may be used without departing from the scope of the embodiments. Also,additional circuits or components may be included as needed. Forexample, in the circuits described above, other than the circuit shownin FIG. 6, the PSU modulator switch Q1 is synced on/off with the Q3 PDisolation switch on/off through data communication or with PD sensinginput voltage/current to switch off and isolate the cable forauto-negotiation. However, when high voltage power is off and lowvoltage power is on at startup, Q3 is off, so an additional circuit maybe included to get power before Q3 to power up with a low voltagecircuit.

Although the method and apparatus have been described in accordance withthe embodiments shown, one of ordinary skill in the art will readilyrecognize that there could be variations made to the embodiments withoutdeparting from the scope of the invention. Accordingly, it is intendedthat all matter contained in the above description and shown in theaccompanying drawings shall be interpreted as illustrative and not in alimiting sense.

1. A method comprising: receiving electrical power at an opticaltransceiver module at a remote network device on a cable deliveringpower on an electrical wire and data on an optical fiber from a centralnetwork device; operating the remote network device in a low voltagemode during fault sensing at the remote network device; transmitting onthe cable, a data signal to the central network device, said data signalindicating an operating status based on said fault sensing; andreceiving high voltage power from the central network device on thecable at the remote network device upon transmitting an indication of asafe operating status, wherein the remote network device is powered bythe high voltage power; wherein the high voltage power comprises highvoltage pulse power and wherein said fault sensing is performed betweenpulses.
 2. The method of claim 1 further comprising auto-negotiatingwith the central network device to identify a type of power to apply atthe remote network device and applying a digital interlock setting apower mode of operation at the remote network device.
 3. The method ofclaim 2 wherein said type of power is chosen from PoE (Power overEthernet) and high voltage pulse power.
 4. The method of claim 1 whereinoperating the remote network device in a low voltage mode comprisesoperating the remote network device in a low voltage mode duringstartup.
 5. The method of claim 1 further comprising providing a pulseload current at the remote network device and fault sensing a powercircuit at the remote network device between pulses in said low voltagemode.
 6. The method of claim 1 wherein the low voltage mode operates atless than 60 volts or less and the high voltage power comprises at least500 volts of power.
 7. (canceled)
 8. The method of claim 7 wherein thehigh voltage power comprises unipolar pulse power.
 9. The method ofclaim 7 wherein the high voltage power comprises bipolar pulse power.10. The method of claim 1 wherein the high voltage power is at least1000 watts and the remote network device is located at a distancegreater than 100 meters.
 11. A method comprising: delivering highvoltage direct current (HVDC) pulse power from power sourcing equipmentto a powered device over a cable delivering power and optical data;testing a power circuit between the power sourcing equipment and thepowered device between high voltage pulses; and communicating with thepowered device over the cable to identify an operating mode at thepowered device based on said testing.
 12. The method of claim 11 whereinthe HVDC pulse power and the data are received at an optical transceivermodule at the powered device.
 13. The method of claim 11 whereincommunicating with the powered device comprises performingauto-negotiation between the power sourcing equipment and powered deviceon the power and optical data cable.
 14. The method of claim 11 whereintesting comprises low voltage sensing of the powered device and cable tocheck for line-to-line faults.
 15. The method of claim 11 furthercomprising delivering low voltage power at the powered device uponstartup of the powered device and receiving an indication that thepowered device is operational before delivering the HVDC pulse power.16. The method of claim 11 wherein the powered device is located atleast 1000 meters from the power sourcing equipment and the HVDC powercomprises at least 1000 watts at peak pulse power.
 17. The method ofclaim 11 wherein the power is pulsed at high power for a duty cycle ofbetween 90% and 95%.
 18. The method of claim 11 wherein a time betweentesting is approximately 1 millisecond.
 19. The method of claim 11further comprising providing a high-resistance midpoint ground toprovide touch-safe line-to-ground protection.
 20. An apparatuscomprising: an optical interface for receiving from a central networkdevice, optical signals on an optical fiber in a power and data cable atan optical transceiver; an electrical interface for receiving from thecentral network device., power on an electrical wire in the power anddata cable at the optical transceiver for powering the apparatus in ahigh power mode greater than 100 watts; and a power module for testing apower circuit and delivering data comprising an operating status of thepower circuit over the power and data cable to a combined power and datasource; wherein the power module is configured for testing the powercircuit in a low voltage power mode.
 21. The apparatus of claim 20wherein the power module is configured to detect a type of powerreceived at the apparatus and select a delivery method for the powerbased on the detected type of power.
 22. The apparatus of claim 20wherein the high power mode comprises pulse power and the low powervoltage mode occurs between pulses.
 23. The apparatus of claim 20wherein the apparatus comprises a powered device located at a distanceof over 100 meters from the combined power and data source in apoint-to-point connection, the combined power and data source deliveringhigh voltage power of at least 1000 watts.
 24. The apparatus of claim 20wherein the power module comprises a low voltage sensing circuit foridentifying line-to-line faults in a cable or the apparatus.
 25. Theapparatus of claim 20 wherein the power circuit comprises ahigh-resistance midpoint ground circuit for providingground-fault-detection and ground-fault-isolation.
 26. The apparatus ofclaim 20 further comprising a connector for mating with the power anddata cable, the connector comprising an insulated connector withshort-pins for touch-safe protection.
 27. The apparatus of claim 20wherein the low voltage power mode operates at 60 volts or less andpower is delivered from the combined power and data source at 500 voltsor higher.
 28. The apparatus of claim 20 wherein the power module isoperable to discharge cable capacitance upon fault detection.
 29. Theapparatus of claim 20 wherein the power module is operable to calculatedroop voltage for use in fault sensing.
 30. The method of claim 1wherein the high voltage pulse power comprises high voltage directcurrent load pulse power at a power level greater than 100 watts.